oliphant at ee.byu.edu
Mon Feb 7 12:38:17 EST 2005
> It's interesting that SciPy and matplotlib really do have much the
> same goal, but taken from different tacks: SciPy focused on the
> computational functionality, and matplotlib on the plotting. However,
> what's become really clear in this discussion is that a good
> scientific math environment really needs both, and they need to be
> well integrated.
The problem was that we needed someone like John to join us on the scipy
effort to get the plotting working well. Our team lacked someone with
his skill. All of us working on SciPy would have loved to work with
him. So, I have nothing but respect for John and his efforts. I just
wish we at SciPy were better recruiters :-)
> I'm optimistic that we can all work together to get that: One set of
> packages that work together to do everything we all need. As someone
> else on this thread mentioned, most of the individual functionality is
> all there, what's mostly need now is for it all to be packaged well
> and work together well. At the core of that is the numarray/NumPy
> unification: I hope Numeric will get us there.
Yes, I think the numarray / Numeric split has been one of the biggest
> One question, Travis: Why did you decide to bring numarray stuff into
> the Numeric code base, rather than the other way around? What I've
> gathered is that the only real show-stopper with numarray is array
> creation speed. Is that really impossible to fix without a complete
A great question. People deserve to hear what I think even if they
disagree with me, so here is a summary of the issues I'm concerned about
with numarray. The basic answer to the question, is that I feel that
numarray is too different structurally (i.e. the classes and objects
that get defined) from Numeric and some of these differences are causing
the speed issues. I felt it would be too much work
to adapt numarray to the Numeric structure than adapt Numeric to the
Here are some specifics.
1) Numarray did not seem to build on Numeric at all. It has thrown out
far too much. As just one example, the ufunc object in Numeric is a
pretty good start, but numarray decided to completely change the
interface for reasons that I do not understand. One result of this
decision is that numarray still does not provide a similar C-API for the
creation of ufuncs that Numeric did.
2) Basic numarray _ndarray C object is way too big. numarray added too
many things to the underlying C-structure of an arrayobject. I think
this will have small-array performance implications.
3) While prototyping in Python was a good idea. Numarray should have
moved the entire object to C and not left so many things to the Python
level. I don't think there should be a Python-level arrayobject as the
basic class (except for RecordArrays). I think this move must still
be done to solve the speed issues, and I see this has much harder than
fixing Numeric which is already all in C.
4) The numarray C-API seems way too big. There are so many, seemingly
repeated calls that seem to do the same thing. Are all of these API
calls really necessary?
5) Numarray builds fundamentally on Int16, Int32, and Float32 objects.
I understand the need for this in many applications, but some users will
still need a way to define arrays based on the c-type that is desired.
In addition, as the mapping from bit-width to c-type is quite platform
dependent, this needs to be done more carefully.
I'm not looking to debate these issues, because I agree that other
opinions may be valid, I could be wrong, and the debate will just
distract me. But, fundamentally, my decision was based on a gut-feel
influenced no doubt by my familiarity and appreciation of the Numeric
code base. If I'm wrong it will be apparent in a couple of months.
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